John is driving a car at 30 km/hr speed. He drove for half an hour and then he changed his speed to 60km/hr and drove for another half an hour. The total distance covered by John (in km) is ___ .

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Solution

John drove the first 30 minutes at 30 km/hr and then changed his speed to 60 km/hr for the next 30 mins. Hence, total distance travelled by John will be the distance he covers in the entire 1 hour.

Time = 0.5 hr

Speed = 30 km/hr

Distance covered = speed × time = 30 × 0.5 = 15 km

Now, new speed = 60 km/hr

Time = 0.5 hr

Distance covered = speed × time = 60 × 0.5 = 30 km

Total distance covered by him = 15 + 30 = 45 km in one hour.

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